Cathode-ray tube wavemeter



Aug 26, 1952 H. HURvlTz cATHoDE-RAY TUBE WAVEMETER Filed Feb. 6, 1948 IN V EN TOR.

Patented Aug. 26,V 1952 l mesne assignments, to Marcel Wallace, .doing business `as Panoramic Laboratories, E'ast Portchester, ConnI `Applicaton-'Febrliary 6, 1948, Serial 'No. 63625 i f1` Th-isinvention relates generally towave meters and more particularly to wave meters'in which `the character of` a wave under investigation is investigatedby applying .the wave directly 'to 'causeldeiiecton of an exploratory beam of electrous. Y y

Wavemeters of the typegenerally known to thepriorart-measure thewave length of electromagnetic energyby determining the tuning of a rcircuit, which, when subjected to the waves, provides-maximum response thereto. In operation the-circuit must be tuned over a range of values,

in order to discover the frequency of maximum response, which is, in itself, a .time consuming process. Further, the circuit must be calibrated,

.foraccurate-work, and this calibration is subject 5to variation with time and` with ambient condi- `ditions. `The structures adaptable for use at ultra high frequencies, say of the order `of 1 to 30 fcentimeters, are expensive ofconstruction, cumbersome and slow in use, and generally unadapted .for rapid measurement.

In the practise of the presentY invention the `-waveof .electromagnetic energy to be studied is Wcoupled to a section of waveguide or to a par- .allel line transmission line, which may be terminated in either an open or a short circuit, so that 'standing waves may be set up therein. The line orthefguidemay be located interiorly of a cath- `oderay'tube oscilloscope, and extend transversely to the'path of travel of the electron beam thereof. The cathode ray beam may be caused to scan at a relatively slow rate across the guide or the line, being influenced ateach transverse i, position by the electric field existing therein, and being deflected thereby in a direction transverse to the direction of scanning motion of the beam. If the length'of` the guide or line is shorter than a 1A; wave length of the electromagnetic energy tapplied thereto, a `null or nodal pointlwill exist VLas well-asmaxima of wave energy. Determination -Lof "the position 4of the -null or nodal point is iiequivalentto measurement of the wave length of f'fthe appliedwave.

i r"-'ffthe'applied-wave has-a quarter wave length 'fbetween two and three times the length of the lineior g'uide,tWo-nulls or nodeswill appear and for shorter waves --additional nulls or nodes. The 'system, accordingly;providesa rapidsystem of measuring Wave length over a wide range of values without requiring adjustments of the Wave meter, the latter being held merely in coupling relation to the source of energy the frequency of which is to be measured, and providing an im mediate and accurate measurement.

`1 ciaim. (c1. isis-45) The structura'ldetails ofthe system-mayrlfall intwo classes. vIn one of the-classes .theguideuor line may extend externally of the envelopebf the cathoderay tube, enablingraddition. of yguide or linelsections thereto, wherebyto 4extendath-e ,range of -Wave lengths measurableby-means -of the apparatus. This advantage. is, Avhowever, .accomplished at the cost of rendering thetubemore fragile and-difficult tomanufacture, byirceasonuof the Ametallic seals required. v

The alternative constructionenvisages:a line or guide section locatedentirely withinthetuba and-coupled to external. sources throughthe glass of the tube. This embodiment, while not as .flexible in use asthe preceding embodimentiis relatively'simple to manufacture, and is as strongand leakproof as a cathode ray'tube of conventional character.

It is, accordingly, '.anobject of the invention, Vto provide acathode ray indicatortube containing electrodes which adapt the tube-for measuring t wave length.

It is a further object ofthe 'invention-tommvidea wave meter comprisingza -wavefguide'or transmission line section located interiorly .of fia cathode ray tube, and'havingj` provisions fornitilizinga cathode ray beam for exploring-.the-fcharacterl of the wave Apatterns Vof `electronlagnetic energy established in theguide or @across nthe transmission line.

VThe above and stillfurtherV objects andaadyantages of the present invention will become evident 'upon studyof the following detailed `description of various embodiments lthereoespeciallywvhen takenin conjunction with the accompanying drawings, wherein: i

AFigure 1 is a longitudinal s section, taken in iplan, of acathode raytube. arranged ineaccordance with .the invention;

Figure 2 4is a' modification of :the linvention Lof Figure 3 is ad'etail ofFigurecZ,representinga section taken on'the line -3--3 of Figure'fZ;

Figure4 is amodification of the systemfof'iliig ure 2, shown in' transverse section; land Figure`5 is a modication of the systemofFi'gure 1, shown in transverse section. a

`Referring now toFigures 1 and 2 of the'raw- `ings,'the reference numeral l denotestheglass envelope of a cathode ray tube indicator, having a cathode 2, a control electrode 3, an acceleratingv electrode 4, a focusing yoke 5, and a magnetic screen 6 by means of which the deiiecting electrodes I are shielded from the magnetic influence of the yoke 5. The deflecting electrodes 1 are supplied with sawtooth voltages from a source 8, causing the electron beam 9 to trace repetitively a linear path in a plan parallel to the plane of the paper, and to impinge on a fluorescent coating I2.

The structuredescribed above is common to all the various embodiments of the invention.

Turning now specifically to Figure 1 of the drawings, a pair of parallel conductive rods I are provided which are spaced by a convenient amount, and which occupy. as a pair,V a plane perpendicular to that traced out of the beam 9, which travels therebetween. i

The rods I0 extend completely through the envelope of the tube I, the envelope being sealed at the points of passage. To one end of the transmission line formed by the rods I0 may be coupled, in any desired manner, a source II (conventionally shown) of radio frequency energy, the wave length of which it is desired to measure. At

the other lend of the line may be connected a short circuiting strap F, if desired, or the lines may be left open.

' yReferring to Figure 5 of the drawings, a structure similar to that of Figure 1 is shown, but with -thelectrodes Illa located entirely within the envelope I, the rods Illa being cemented vto the inf' terior wall of the envelope I. In the embodiment of Figure 5, energy from a source of R. F. energy may be coupled by locating one end of the line I 0a adjacent the source, coupling taking place by A'induction through the glass.

In the case of both Figure 1 and Figure 5 the energyA applied to the transmission lines I0 or Ilia, respectively, will give rise to standing waves across the line, by reason of the totally reiiecting 'termination of the line. The electron beam 9 in tracing between the conductors of the line will be subjected at each point in its passage to an alternating electric field, having a magnitude equal to lthat of the standing wave at the point. A correspending deflection of the beam 9 will occur,

"which will make itself evident as a visible picture *of the shape of the wave on the fluorescent material F coated on the face of the tube I. This picture will contain one or more nodes or nulls, the location of which will be immediately indica- `vtive of the wave length of thewave impressed on the lines I0 or Illa, since these nulls or'nodes correspond in location with nulls or nodes in the i standing wave of electromagnetic energy present Yonzthe lines. vf ITurning now .to Figure 2 of the drawings, it will be: evident Athatfor the line I0 has been substituted a section of wave guide I3, extending externally of the envelope of the tube I at each end thereof, and in sealed relation thereto. The interior passage of the guide I3' itself is sealed'at each end by glass windows I4, in accordance with known-techniques, in order to keep the envelope I being located inthe plane of scanning of thebeam 9 in response Y solely to the voltage applied to electrodes 1. A

, Reference maybe had'to Figure lof the draw- ,ingswhereinis illustrated in transverse section 4 a structure similar to that of Figure 2, except that the wave guide section I3a illustrated in Figure 4 does not extend externally of the envelope I but is located entirely within the envelope I. The wave guide section I3a may be closed at one end by a metallic plug I6. and open at the other end l1.

The section I5, on the other hand, may be left open at both ends, and the load end may be plugged by means of a plunger, if desired, or extensions of the guide section I5 may be added, as desired, and as the exigencies of particular situations may demand.

The advantage of the embodiment of Figure 4,'

with respect to that of Figure 2, is that the envelope and guide sealing problems present in the embodiment of Figure 2 are obviated in the embodiment of Figure 5.

Energy may be coupled to the wave guide section I3a through the envelope I, merely by holding the open end -I'I of the guide source of such energy. Y v

While I have described several embodiments of the present invention, it will be clear that modifications of the structure may be resorted to without departing from the true scope of the invention, as dened in the appended claim.

What I claim and desire to secure by Letters Patent of the United States is:

A cathode ray tube wave meter for visually indicating directly the Wave length of electromagnetic Wave energy deriving from a source of such energy, comprising, means for generating a beam of electrons, a fluorescent viewing screen adapted to provide avisible indication in response to impact by said beam of electrons,.meansfor directing said beam. of electrons' against said screen, means for` sweeping said beam of `electrons across said screen in a predetermined path, guiding means for guiding said electromagnetic wave energy in space, said guidingmeans having an input and a termination at opposite ends thereof, means for coupling said input tol said source of wave energy, said termination being of the type which provides total reiiection of said wave energy and thereby establishes a standing Wave pattern only of said Wave'energy 4in said guiding means, said guiding means vso located with respect to said path that said beam of electrons 'sweeps through said'standing wave pattern in sweeping in said predetermined path. y

. HYMAN HURVITZ.

REFERENCES CITED v smuuin et @1.1 oct, V5,1948

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